Crosslinkable polymeric compositions for flexible crosslinked cable insulation and methods for making flexible crosslinked cable insulation

ABSTRACT

Crosslinkable polymeric compositions comprising: (a) a polymer blend comprising: (1) 10 to 94 weight percent, based on the total weight of the crosslinkable polymeric composition, of an ethylene-based interpolymer having the following properties: (i) a density of 0.93 g/cm 3  or less, (ii) a melt index (I 2 ) at 190° C. of greater than 0.2 g/10 minutes, and (iii) a shear thinning ratio (V0.1/V100) at 190° C. and 10% strain of less than 8; and (2) 5 to 90 weight percent, based on the total weight of the crosslinkable polymeric composition, of a high-pressure polyethylene; and (b) 0 to less than 40 weight percent, based on the total weight of the crosslinkable polymeric composition, of a filler, where the ethylene-based interpolymer of component (a) is not prepared in a high-pressure reactor or process. Additionally, the polymer blend has the following properties: (i) a shear thinning ratio (V0.1/V100) at 190° C. and 10% strain of at least 5, (ii) a high-shear viscosity (V100) at 190 C and 10% strain of less than 1,300 Pa·s, (iii) a melt strength of at least 4 centiNewtons at 190° C., and (iv) a flexural modulus, 2% secant, of less than 25,000 psi. Such crosslinkable polymeric compositions may be employed as insulation layers in flexible power cables.

REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/247,806, filed on Oct. 29, 2015.

FIELD

Various embodiments of the present invention relate to crosslinkablepolymeric compositions for making flexible crosslinked cable insulation.

INTRODUCTION

The crosslinked insulation layer of flexible power cables is generallymade of compounds comprising ethylene/propylene (“EP”) orethylene/propylene/diene monomer (“EPDM”) polymers. These EP and EPDMinterpolymers typically have a relatively high melt viscosity (e.g., asevidenced by a relatively low melt index, such as an 12 of less than 0.2g/10 minutes). Such interpolymers require fillers, such as calcinedclay, to assure adequate pellet stability and melt strength (or zeroshear viscosity or extensional viscosity) for sag resistance duringextrusion. However, the high melt viscosity and filler content of thesepolymers reduces the speed at which they can be extruded during cablemanufacturing. Furthermore, the incorporation of filler increases thedensity of the insulation composition, which not only increases the massof the fabricated cable but also may result in increased manufacturingcost of the cable. Accordingly, improvements are desired.

SUMMARY

One embodiment is a crosslinkable polymeric composition comprising:

-   -   (a) a polymer blend comprising:        -   (1) 10 to 94 weight percent, based on the total weight of            said crosslinkable polymeric composition, of an            ethylene-based interpolymer having the following properties:            -   (i) a density of 0.93 g/cm³ or less,            -   (ii) a melt index (I₂) at 190° C. of greater than 0.2                g/10 minutes, and            -   (iii) a shear thinning ratio (V0.1/V100) at 190° C. and                10% strain of less than 8; and        -   (2) 5 to 90 weight percent, based on the total weight of            said crosslinkable polymeric composition, of a high-pressure            polyethylene; and    -   (b) 0 to less than 40 weight percent, based on the total weight        of said crosslinkable polymeric composition, of a filler,    -   wherein said ethylene-based interpolymer of component (a) is not        prepared in a high-pressure reactor or process,    -   wherein said polymer blend has the following properties:        -   (i) a shear thinning ratio (V0.1/V100) at 190° C. and 10%            strain of at least 5,        -   (ii) a high-shear viscosity (V100) at 190° C. and 10% strain            of less than 1,300 Pa·s,        -   (iii) a melt strength of at least 4 centiNewtons at 190° C.,            and        -   (iv) a flexural modulus, 2% secant, of less than 25,000 psi.

DETAILED DESCRIPTION

Various embodiments of the present invention concern crosslinkablepolymeric compositions comprising an ethylene-based interpolymer and ahigh-pressure polyethylene. Additional embodiments concern crosslinkedpolymeric compositions prepared from such crosslinkable polymericcompositions. Further embodiments concern coated conductorsincorporating the crosslinkable polymeric compositions.

Crosslinkable Polymeric Composition

As noted above, one component of the crosslinkable polymericcompositions described herein is an ethylene-based interpolymer. As usedherein, “ethylene-based” interpolymers are interpolymers prepared fromethylene monomers as the primary (i.e., at least 50 weight percent (“wt%”)) monomer component, though one or more other co-monomers areemployed. “Polymer” means a macromolecular compound prepared by reacting(i.e., polymerizing) monomers of the same or different type, andincludes homopolymers and interpolymers. “Interpolymer” means a polymerprepared by the polymerization of at least two different monomer types.This generic term includes copolymers (usually employed to refer topolymers prepared from two different monomer types), and polymersprepared from more than two different monomer types (e.g., terpolymers(three different monomer types) and quaterpolymers (four differentmonomer types)).

In an embodiment, the ethylene-based interpolymer can be anethylene/alpha-olefin (“α olefin”) interpolymer having an α-olefincontent of at least 1 wt %, at least 5 wt %, at least 10 wt %, at least15 wt %, at least 20 wt %, or at least 25 wt % based on the entireinterpolymer weight. These interpolymers can have an α-olefin content ofless than 50 wt %, less than 45 wt %, less than 40 wt %, or less than 35wt % based on the entire interpolymer weight. When an α-olefin isemployed, the α-olefin can be a C₃₋₂₀ (i.e., having 3 to 20 carbonatoms) linear, branched or cyclic α-olefin. Examples of C₃₋₂₀ α-olefinsinclude propene, 1 butene, 4-methyl-1-pentene, 1-hexene, 1-octene,1-decene, 1 dodecene, 1 tetradecene, 1 hexadecene, and 1-octadecene. Theα-olefins can also have a cyclic structure such as cyclohexane orcyclopentane, resulting in an α-olefin such as 3 cyclohexyl-1-propene(allyl cyclohexane) and vinyl cyclohexane. Illustrativeethylene/α-olefin interpolymers include ethylene/propylene,ethylene/1-butene, ethylene/1 hexene, ethylene/1-octene,ethylene/propylene/1-octene, ethylene/propylene/1-butene, andethylene/1-butene/1-octene.

In various embodiments, the ethylene-based interpolymer can furthercomprise a non-conjugated diene comonomer. Suitable non-conjugateddienes include straight-chain, branched-chain or cyclic hydrocarbondienes having from 6 to 15 carbon atoms. Examples of suitablenon-conjugated dienes include, but are not limited to, straight-chainacyclic dienes, such as 1,4-hexadiene, 1,6-octadiene, 1,7-octadiene, and1,9-decadiene; branched-chain acyclic dienes, such as5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene,3,7-dimethyl-1,7-octadiene, and mixed isomers of dihydromyricene anddihydroocinene; single-ring alicyclic dienes, such as1,3-cyclopentadiene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, and1,5-cyclododecadiene; and multi-ring alicyclic fused and bridged-ringdienes, such as tetrahydroindene, methyl tetrahydroindene,dicyclopentadiene, and bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl,alkylidene, cycloalkenyl, and cycloalkylidene norbornenes, such as5-methylene-2-norbornene, 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene, and norbornadiene.Of the dienes typically used to prepare EPDMs, the particularlypreferred dienes are 1,4-hexadiene (“HD”), 5-ethylidene-2-norbornene(“ENB”), 5-vinylidene-2-norbornene (“VNB”), 5-methylene-2-norbornene(“MNB”), and dicyclopentadiene (“DCPD”). The most especially preferreddiene is ENB. When present, the diene content of the ethylene-basedinterpolymer can be in the range of from 0.1 to 10.0 wt %, from 0.2 to5.0 wt %, or from 0.3 to 3.0 wt %, based on the entire interpolymerweight.

In an embodiment, the ethylene-based interpolymer can be anethylene/α-olefin elastomer. In various embodiments, when a dienecomonomer is employed, the ethylene-based interpolymer can be anethylene/α-olefin/diene comonomer interpolymer, such as anethylene/propylene/diene comonomer interpolymer.

In an embodiment, the ethylene-based interpolymer can be selected fromthe group consisting of an ethylene/propylene copolymer, anethylene/1-octene copolymer, an ethylene/propylene/diene comonomerterpolymer, and combinations of two or more thereof. In an embodiment,the ethylene-based interpolymer is an ethylene/1-octene copolymer.

When the ethylene-based interpolymer is an ethylene/propylene copolymer,the ethylene can be present in the copolymer in an amount ranging from50.0 to 98.0 wt %, and the propylene can be present in an amount rangingfrom 2.0 to 50.0 wt %, based on the entire interpolymer weight. When theethylene-based interpolymer is an ethylene/1-octene copolymer, theethylene can be present in the copolymer in an amount ranging from 50.0to 95.0 wt %, and the 1-octene can be present in an amount ranging from5.0 to 50.0 wt %, based on the entire interpolymer weight. When theethylene-based interpolymer is an ethylene/propylene/diene comonomerterpolymer, the ethylene can be present in the copolymer in an amountranging from 50.0 to 97.9 wt %, the propylene can be present in anamount ranging from 2.0 to 49.9 wt %, and the diene comonomer can bepresent in an amount ranging from 0.1 to 10 wt %, based on the entireinterpolymer weight.

Ethylene-based interpolymers suitable for use herein have a density of0.93 g/cm³ or less, 0.92 g/cm³ or less, 0.91 g/cm³ or less, 0.90 g/cm³or less, or 0.89 g/cm³ or less. Additionally, ethylene-basedinterpolymers suitable for use herein can have a density of at least0.85 g/cm³, at least 0.86 g/cm³, at least 0.87 g/cm³, or at least 0.88g/cm³. Polymer densities provided herein are determined according toASTM International (“ASTM”) method D792.

Ethylene-based interpolymers suitable for use herein can have ahigh-shear viscosity (V100) at 100 s⁻¹, 190° C. and 10% strain of 2,000Pa·s or less, less than 1,600 Pa·s, less than 1,200 Pa·s, less than1,100 Pa·s, or less than 1,000 Pa·s. Additionally, ethylene-basedinterpolymers suitable for use herein can have a high-shear viscosity ofat least 200 Pa·s under the same conditions. High-shear viscosity isdetermined according to the procedure provided in the Test Methodssection, below.

Ethylene-based interpolymers suitable for use herein can have a shearthinning ratio (V0.1/V100) at 190° C. and 10% strain of less than 8,less than 7, less than 6, less than 5, or less than 4. Additionally,ethylene-based interpolymers suitable for use herein can have a shearthinning ratio of at least 0.1, at least 1, or at least 2. Shearthinning ratio is determined according to the procedure provided in theTest Methods section, below.

In an embodiment, the ethylene-based interpolymer can have a melt index(I₂) of greater than 0.2 g/10 min., at least 0.3 g/10 min., at least 0.5g/10 min., at least 0.7 g/10 min., at least 1.0 g/10 min., at least 1.5g/10 min., at least 2.0 g/10 min., or at least 2.5 g/10 min. In thisembodiment, the ethylene-based interpolymer can have a melt index (I₂)of less than 10 g/10 min., less than 7 g/10 min., or less than 5 g/10min. In various embodiments, the ethylene-based interpolymer can have amelt index (I₂) in the range of from 2.0 to 5.0 g/10 min. Melt indicesprovided herein are determined according to ASTM method D1238. Unlessotherwise noted, melt indices are determined at 190° C. and 2.16 Kg(i.e., I₂).

Ethylene-based interpolymers suitable for use herein can have apolydispersity index (“PDI,” or the ratio of weight-averaged molecularweight (Mw) to number-averaged molecular weight (Mn)) in the range offrom 1 to 10, from 2 to 5, or from 2.0 to 4.3. PDI is determined by gelpermeation chromatography according to the procedure provided in theTest Methods section, below.

Ethylene-based interpolymers suitable for use herein can have a meltstrength at 190° C. in the range of from 0.1 to 20 centiNewtons (“cN”),from 0.5 to 10 cN, or from 0.7 to 5 cN. Melt strength is determinedaccording to the procedure provided in the Test Methods section, below.

In one or more embodiments, the ethylene-based interpolymer is notprepared in a high-pressure reactor or process. As used herein, the term“high-pressure reactor” or “high-pressure process” is any reactor orprocess operated at a pressure of at least 5000 psi. As known to thoseof ordinary skill in the art, polyethylenes prepared in a high-pressurereactor or process tend to have a highly branched polymer structure,with branches found both on the polymer backbone and on the branchesthemselves. In contrast, the ethylene-based interpolymer describedherein can be a substantially linear polymer. As used herein, the term“substantially linear” denotes a polymer having a backbone that issubstituted with 0.01 to 3 long-chain branches per 1,000 carbon atoms.In some embodiments, the ethylene-based interpolymer can have a backbonethat is substituted with 0.01 to 1 long-chain branches per 1,000 carbonatoms, or from 0.05 to 1 long-chain branches per 1,000 carbon atoms.

Long-chain branching is defined herein as a chain length of at least 6carbon atoms, above which the length cannot be distinguished by ¹³Cnuclear magnetic resonance (“¹³C NMR”) spectroscopy. Long-chain branchescan have a length up to about the same length as the polymer backbone.Long-chain branching is determined by ¹³C NMR spectroscopy and isquantified using the method of Randall (Rev. Macromol. Chem. Phys., C29(2&3), p. 285-297), the disclosure of which is incorporated herein byreference.

In an embodiment, the ethylene-based interpolymers can be polymers knownas linear olefin polymers which have no long-chain branching. That is, a“linear olefin polymer” has an absence of long-chain branching, as forexample the traditional linear-low-density polyethylene orlinear-high-density polyethylene polymers or ethylene propylene or EPDMmade using Ziegler polymerization processes (e.g., as taught in U.S.Pat. Nos. 4,076,698 and 3,645,992).

Suitable processes useful in producing the ethylene-based interpolymers,including the use of use of multiple loop reactors operating in seriesand a variety of suitable operating conditions for use therewith, may befound, for example, in U.S. Pat. Nos. 5,977,251, 6,545,088, 6,319,989,and 6,683,149. In particular, the polymerization is carried out as acontinuous polymerization, preferably a continuous solutionpolymerization, in which catalyst components, monomers, and optionallysolvent, adjuvants, scavengers, and polymerization aids are continuouslysupplied to one or more reactors or zones and polymer productcontinuously removed therefrom. Within the scope of the terms“continuous” and “continuously” as used in this context are thoseprocesses in which there are intermittent additions of reactants andremoval of products at small regular or irregular intervals so that,over time, the overall process is substantially continuous. Due to thedifference in monomers, temperatures, pressures or other differences inpolymerization conditions between at least two of the reactors or zonesconnected in series, polymer segments of differing composition such ascomonomer content, crystallinity, density, tacticity, regio-regularity,or other chemical or physical difference within the same molecule areformed in the different reactors or zones.

Each reactor in the series can be operated under solution, slurry, orgas-phase polymerization conditions. In a multiple-zone polymerization,all zones operate under the same type of polymerization, such assolution, slurry, or gas phase, but at different process conditions. Fora solution polymerization process, it is desirable to employ homogeneousdispersions of the catalyst components in a liquid diluent in which thepolymer is soluble under the polymerization conditions employed. Onesuch process utilizing an extremely fine silica or similar dispersingagent to produce such a homogeneous catalyst dispersion wherein normallyeither the metal complex or the cocatalyst is only poorly soluble isdisclosed in U.S. Pat. No. 5,783,512. A slurry process typically uses aninert hydrocarbon diluent and temperatures of from 0° C. up to atemperature just below the temperature at which the resulting polymerbecomes substantially soluble in the inert polymerization medium.Preferred temperatures in a slurry polymerization are from 30° C.,preferably from 60° C. up to 115° C., preferably up to 100° C. Pressurestypically range from atmospheric (100 kPa) to 500 psi (3.4 MPa). In anembodiment, the ethylene-based interpolymer is prepared using solutionpolymerization.

In all of the foregoing processes, continuous or substantiallycontinuous polymerization conditions can be employed. The use of suchpolymerization conditions, especially continuous, solutionpolymerization processes, allows the use of elevated reactortemperatures which results in economical production and efficiencies.

The catalyst may be prepared as a homogeneous composition by addition ofthe requisite metal complex or multiple complexes to a solvent in whichthe polymerization will be conducted or in a diluent compatible with theultimate reaction mixture. The desired cocatalyst or activator and maybe combined with the catalyst composition either prior to,simultaneously with, or after combination of the catalyst with themonomers to be polymerized and any additional reaction diluent.

At all times, the individual ingredients as well as any active catalystcomposition must be protected from oxygen, moisture and other catalystpoisons. Therefore, the catalyst components, shuttling agent andactivated catalysts must be prepared and stored in an oxygen- andmoisture-free atmosphere, preferably under a dry, inert gas such asnitrogen.

An exemplary polymerization process for producing the ethylene-basedinterpolymer is as follows. In one or more well stirred tank or loopreactors operating under solution polymerization conditions, themonomers to be polymerized are introduced continuously together with anysolvent or diluent at one part of the reactor. The reactor contains arelatively homogeneous liquid phase composed substantially of monomerstogether with any solvent or diluent and dissolved polymer. Preferredsolvents include C₄₋₁₀ hydrocarbons or mixtures thereof, especiallyalkanes such as hexane or mixtures of alkanes, as well as one or more ofthe monomers employed in the polymerization.

Catalyst and cocatalyst are continuously or intermittently introduced inthe reactor liquid phase or any recycled portion thereof at a minimum ofone location. The reactor temperature and pressure may be controlled byadjusting the solvent/monomer ratio, the catalyst addition rate, as wellas by use of cooling or heating coils, jackets or both. Thepolymerization rate is controlled by the rate of catalyst addition. Thecontent of a given monomer in the polymer product is influenced by theratio of monomers in the reactor, which is controlled by manipulatingthe respective feed rates of these components to the reactor. Thepolymer product molecular weight is controlled, optionally, bycontrolling other polymerization variables such as the temperature,monomer concentration, or a chain-terminating agent such as hydrogen, asis well known in the art. Connected to the discharge of the reactor,optionally by means of a conduit or other transfer means, is a secondreactor, such that the reaction mixture prepared in the first reactor isdischarged to the second reactor without substantial termination ofpolymer growth. Between the first and second reactors, a differential inat least one process condition is established. Preferably for use information of an interpolymer of two or more monomers, the difference isthe presence or absence of one or more comonomers or a difference incomonomer concentration. Additional reactors, each arranged in a mannersimilar to the second reactor in the series may be provided as well.Upon exiting the last reactor of the series, the effluent is contactedwith a catalyst kill agent such as water, steam, or an alcohol or with acoupling agent.

The resulting polymer product is recovered by flashing off volatilecomponents of the reaction mixture such as residual monomers or diluentat reduced pressure, and, if necessary, conducting furtherdevolatilization in equipment such as a devolatilizing extruder. In acontinuous process, the mean residence time of the catalyst and polymerin the reactor generally is from 5 minutes to 8 hours, or from 10minutes to 6 hours.

Alternatively, the foregoing polymerization may be carried out in a plugflow reactor with a monomer, catalyst, shuttling agent, temperature orother gradient established between differing zones or regions thereof,optionally accompanied by separated addition of catalysts and/or chainshuttling agent, and operating under adiabatic or non-adiabaticpolymerization conditions.

The catalyst employed in preparing the ethylene-based interpolymer canbe selected from those described in U.S. Pat. No. 8,202,953 B2 fromcolumn 10, line 32, to column 18, line 53, which is incorporated hereinby reference. In an embodiment, the catalyst employed in preparing theethylene-based interpolymer can bebis(2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-(4-(2-methyl)propane-2-yl)-2-phenoxy)-1,3-propanediylzirconium (IV) dichloride, which has the following structure:

The catalyst may be conveniently prepared by standard metallation andligand exchange procedures involving a source of the transition metaland a neutral polyfunctional ligand source. In addition, the catalystmay also be prepared by means of an amide elimination andhydrocarbylation process starting from the corresponding transitionmetal tetraamide and a hydrocarbylating agent, such astrimethylaluminum. The techniques employed are the same as or analogousto those disclosed in U.S. Pat. Nos. 6,320,005 and 6,103,657; PCTPublished Patent Application Nos. WO 02/38628 and WO 03/40195; U.S.Published Patent Application No. 2004/0220050, and elsewhere.

The polymerization catalyst may be activated to form an active catalystcomposition by combination with one or more cocatalysts, preferably acation-forming cocatalyst, a strong Lewis acid, or a combinationthereof. Suitable cocatalysts for use include polymeric or oligomericaluminoxanes, especially methyl aluminoxane, as well as inertcompatible, noncoordinating ion-forming compounds. So-called modifiedmethyl aluminoxane (“MMAO”) or triethyl aluminum (“TEA”) are alsosuitable for use as cocatalysts. One technique for preparing suchmodified aluminoxane is disclosed in U.S. Pat. No. 5,041,584 (Crapo etal.). Aluminoxanes can also be made as disclosed in U.S. Pat. No.5,542,199 (Lai et al.); U.S. Pat. No. 4,544,762 (Kaminsky et al.); U.S.Pat. No. 5,015,749 (Schmidt et al.); and U.S. Pat. No. 5,041,585(Deavenport et al.).

The ethylene-based interpolymer can be present in the crosslinkablepolymeric composition in an amount ranging from 10 to 94 wt %, from 20to 94 wt %, from 30 to 94 wt %, from 40 to 94 wt %, from 50 to 94 wt %,from 60 to 94 wt %, from 70 to 94 wt %, from 80 to 94 wt %, or from 90to 94 wt %, based on the entire weight of the crosslinkable polymericcomposition.

As noted above, the crosslinkable polymeric composition furthercomprises a polyethylene prepared by a high-pressure process or reactor,such as a high-pressure low-density polyethylene (“HP LDPE”).High-pressure polyethylenes suitable for use herein can have a meltstrength at 190° C. of greater than 4 cN, at least 6 cN, or at least 8cN. Additionally, high-pressure polyethylenes suitable for use can havea melt strength at 190° C. in the range of from 4 to 30 cN, from 6 to 20cN, or from 8 to 15 cN.

High-pressure polyethylenes are prepared by high-pressure processes thatare typically free-radical-initiated polymerizations and conducted in atubular reactor or a stirred autoclave or a combination of the two. In atubular reactor, the pressure can be in the range of from 25,000 to45,000 pounds per square inch (psi), and the temperature can be in therange of from 200 to 350° C. In a stirred autoclave, the pressure can bein the range of from 10,000 to 30,000 psi, and the temperature can be inthe range of from 175 to 250° C.

High-pressure polyethylenes include interpolymers comprised of ethylene,unsaturated esters and/or hydrolyzable silane monomers that are wellknown and can be prepared by conventional high-pressure processes orpost-reactor modification. In various embodiments, the unsaturatedesters can be alkyl acrylates, alkyl methacrylates, or vinylcarboxylates. The alkyl groups can have from 1 to 8 carbon atoms, orfrom 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8carbon atoms, or from 2 to 5 carbon atoms.

Examples of acrylates and methacrylates include, but are not limited to,ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate,n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate.Examples of vinyl carboxylates include, but are not limited to, vinylacetate, vinyl propionate, and vinyl butanoate.

Such high-pressure polyethylenes generally have a density ranging fromabout 0.91 to about 0.94 g/cm³. In various embodiments, thehigh-pressure polyethylene is a high-pressure LDPE having a density ofat least 0.915 g/cm³, but less than 0.94 g/cm³, or less than 0.93 g/cm³.HP LDPEs suitable for use herein can have a melt index (I₂) of less than20 g/10 min., or ranging from 0.1 to 10 g/10 min., from 0.2 to 8 g/10min., from 0.3 to 5 g/10 min, or from 0.4 to 3 g/10 min. Additionally,such HP LDPEs generally have a broad molecular weight distributionresulting in a high polydispersity index. The high-pressure polyethylenecan be present in an amount of greater than 0 but less than 90 wt %,from 5 to less than 70 wt %, from 10 to less than 50 wt %, from 15 toless than 40 wt %, or from 20 to 35 wt %, based on the total weight ofthe crosslinkable polymeric composition.

Suitable commercially available high-pressure polyethylenes include, butare not limited to, DFDA-1216 NT available from The Dow ChemicalCompany, BPD2000E available from INEOS Olefins and Polymers Europe, andLDPE 2102TX00 available from SABIC Europe.

In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can exhibit surprisingly improved properties.In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can exhibit a shear thinning ratio(V0.1/V100) at 190° C. and 10% strain of at least 10% greater, at least15% greater, at least 20% greater, at least 25% greater, at least 50%greater, at least 75% greater, or at least 100% greater than the shearthinning ratio of the unmodified ethylene-based interpolymer.Additionally, the shear thinning ratio of a blend of the ethylene-basedinterpolymer and the high-pressure polyethylene can be at least 5, atleast 5.5, or at least 6.

In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a high-shear viscosity (V100) at190° C. and 10% strain of less than 1,300 Pa·s, less than 1,200 Pa·s,less than 1,100 Pa·s, less than 1,000 Pa·s, or less than 950 Pa·s. Insuch embodiments, the blend can have a high-shear viscosity under thesame conditions of at least 500 Pa·s.

Furthermore, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a melt strength at 190° C. of atleast 4 cN, at least 5 cN, at least 6 cN, at least 7 cN, or at least 8cN. In such embodiments, the blend can have a melt strength up to 20 cN.Additionally, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can exhibit a melt strength at 190° C. of atleast 50% greater, at least 100% greater, at least 200% greater, atleast 300% greater, at least 400% greater, or at least 500% greater thanthe melt strength of the unmodified ethylene-based interpolymer. In suchembodiments, the blend can exhibit a melt strength up to 1,000% greaterthan the melt strength of the unmodified ethylene-based interpolymer.

Additionally, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a melt discharge temperature whilebeing extruded on a 2.5-inch 24:1 L/D extruder using a Maddock screw and20/40/60/20 mesh screens (at set temperatures of 115.6° C. across allfive zones, head and the die) at a screw speed of 100 rpm of less than190° C., less than 185° C., or less than 180° C. Melt dischargetemperatures are determined according to the procedure provided in theTest Methods section, below.

In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a maximum extensional viscosity ofgreater than 100,000 psi, greater than 150,000 psi, or greater than200,000 psi when measured at 135° C. and 1 s⁻¹ (at any Hencky strain).In such embodiments, the blend can have a maximum extensional viscosityup to 1,000,000 psi (at any Hencky strain).

In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a zero shear viscosity at 135° C. ofat least 5,000 Pa·s, at least 10,000 Pa·s, or at least 15,000 Pa·s.Additionally, the blend can have a zero shear viscosity at 135° C. of upto 300,000 Pa·s.

In various embodiments, a blend of the ethylene-based interpolymer andhigh-pressure polyethylene can have a flexural modulus, 2% secant ofless than 25,000 psi, less than 20,000 psi, less than 15,000 psi, lessthan 10,000 psi, or less than 8,000 psi. In such embodiments, the blendcan have a flexural modulus, 2% secant under the same conditions of atleast 1,000 psi.

In one or more embodiments, blends of the ethylene-based interpolymerand high-pressure polyethylene exhibiting the foregoing properties cancomprise the ethylene-based interpolymer in an amount ranging from 60 to95 wt %, 62 to 90 wt %, from 65 to 85 wt %, or from 65 to 80 wt %, basedon the combined weight of the ethylene-based interpolymer andhigh-pressure polyethylene. Additionally, such blends can comprise thehigh-pressure polyethylene in an amount ranging from 5 to 40 wt %, 10 to38 wt %, from 15 to 35 wt %, or from 20 to 35 wt %, based on thecombined weight of the ethylene-based interpolymer and high-pressurepolyethylene.

As noted above, the polymeric compositions described herein arecrosslinkable. The term “crosslinkable” means that the polymericcomposition contains one or more additives or modifications that enhancethe ethylene-based interpolymer's and high-pressure polyethylene'sability to crosslink when subjected to crosslinking conditions (e.g.,heat, irradiation, or moisture). In one or more embodiments, thepolymeric composition can be rendered crosslinkable by furthercomprising an organic peroxide. Organic peroxides suitable for useherein include mono-functional peroxides and di-functional peroxides. Asused herein, “mono-functional peroxides” denote peroxides having asingle pair of covalently bonded oxygen atoms (e.g., having a structureR—O—O—R). As used herein, “di-functional peroxides” denote peroxideshaving two pairs of covalently bonded oxygen atoms (e.g., having astructure R—O—O—R—O—O—R). In an embodiment, the organic peroxide is amono-functional peroxide.

Exemplary organic peroxides include dicumyl peroxide (“DCP”); tert-butylperoxybenzoate; di-tert-amyl peroxide (“DTAP”); bis(t-butyl-peroxyisopropyl) benzene (“BIPB”); isopropylcumyl t-butyl peroxide;t-butylcumylperoxide; di-t-butyl peroxide;2,5-bis(t-butylperoxy)-2,5-dimethylhexane;2,5-bis(t-butylperoxy)-2,5-dimethylhexyne-3;1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane; isopropylcumylcumylperoxide; butyl 4,4-di(tert-butylperoxy)valerate;di(isopropylcumyl) peroxide; and mixtures of two or more thereof. Invarious embodiments, only a single type of organic peroxide is employed.In an embodiment, the organic peroxide is dicumyl peroxide.

In various embodiments, the organic peroxide can be present in thecrosslinkable polymeric composition in an amount of at least 0.5 wt %,or in the range of from 0.5 to 5 wt %, from 0.5 to 3 wt %, from 0.5 to2.5 wt %, from 1 to 2.5 wt %, or from 1.5 to 2.5 wt %, based on theentire weight of the crosslinkable polymeric composition.

As an alternative, or in addition, to the use of peroxides to render thepolymeric composition crosslinkable, other approaches for crosslinkingof polymers may be used to effect the desired degree of crosslinking.Such approaches and technologies are well known to those skilled in theart and include (but are not limited to) radiation crosslinking,moisture crosslinking, bisulfonyl azide crosslinking, crosslinking withhydroxyl terminated polydimethylsiloxane, etc. In some cases, it wouldbe necessary for the above-described ethylene-based interpolymer and/orhigh-pressure polyethylene to be functionalized appropriately to enablecrosslinking (for example, with alkoxy silanes in the case of moisturecrosslinking or crosslinking with hydroxyl terminatedpolydimethylsiloxane).

In various embodiments, the ethylene-based interpolymer and/orhigh-pressure polyethylene may be rendered crosslinkable byfunctionalization with a hydrolyzable silane group. As known in the art,when in the presence of water, such hydrolyzable silane groups willundergo a hydrolysis reaction to generate Si—O—Si bonds to form acrosslinking network between polymer chains (a.k.a., moisturecrosslinking or moisture curing). Functionalization of theethylene-based interpolymer and/or high-pressure polyethylene can beaccomplished by either copolymerizing a monomer having a hydrolyzablesilane group with the above-described ethylene and comonomers or bygrafting a hydrolyzable silane group to the backbone of theethylene-based interpolymer in a post-reactor process. Such techniquesare within the capabilities of one having ordinary skill in the art.

Hydrolyzable silane monomers suitable for use in forming asilane-functionalized ethylene-based interpolymer and/or high-pressurepolyethylene can be any hydrolyzable silane monomer that willeffectively copolymerize with an olefin (e.g., ethylene), or graft toand crosslink an olefin (e.g., ethylene) polymer. Those described by thefollowing formula are exemplary:

in which R′ is a hydrogen atom or methyl group; x is 0 or 1; n is aninteger from 1 to 12 inclusive, preferably 1 to 4, and each R″independently is a hydrolyzable organic group such as an alkoxy grouphaving from 1 to 12 carbon atoms (e.g. methoxy, ethoxy, butoxy), anaryloxy group (e.g. phenoxy), an araloxy group (e.g. benzyloxy), analiphatic acyloxy group having from 1 to 12 carbon atoms (e.g.formyloxy, acetyloxy, propanoyloxy), an amino or substituted amino group(alkylamino, arylamino), or a lower-alkyl group having 1 to 6 carbonatoms inclusive, with the proviso that not more than one of the three R″groups is an alkyl. Such silanes may be copolymerized with ethylene in areactor, such as a high-pressure process. Such silanes may also begrafted to a suitable ethylene polymer by the use of a suitable quantityof organic peroxide. Suitable silanes include unsaturated silanes thatcomprise an ethylenically unsaturated hydrocarbyl group, such as avinyl, allyl, isopropenyl, butenyl, cyclohexenyl or gamma (meth)acryloxyallyl group, and a hydrolyzable group, such as, for example, ahydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group. Examples ofhydrolyzable groups include methoxy, ethoxy, formyloxy, acetoxy,proprionyloxy, and alkyl or arylamino groups. Preferred silanes are theunsaturated alkoxy silanes which can be grafted onto the polymer orcopolymerized in-reactor with other monomers (such as ethylene andacrylates). These silanes and their method of preparation are more fullydescribed in U.S. Pat. No. 5,266,627 to Meverden, et al. Suitablehydrolyzable silane monomers include, but are not limited to,vinyltrimethoxysilane (“VTMS”), vinyltriethoxysilane (“VTES”),vinyltriacetoxysilane, and gamma-(meth)acryloxy propyl trimethoxysilane. When included, the silane functional comonomer can constitute inthe range of from 0.2 to 10 wt % of the ethylene-based interpolymer.

In one or more embodiments, the crosslinkable polymeric composition mayoptionally comprise a filler. Fillers suitable for use herein include,but are not limited to, heat-treated clay, surface-treated clay,organo-clay, precipitated silica and silicates, fumed silica, calciumcarbonate, ground minerals, aluminum trihydroxide, magnesium hydroxide,and carbon blacks.

In various embodiments, the crosslinkable polymeric compositioncomprises 0 to less than 40 wt % filler, based on the entire weight ofthe crosslinkable polymeric composition. Additionally, the crosslinkablepolymeric composition can comprise greater than 0 but less than 40 wt %,less than 30 wt %, less than 20 wt %, less than 10 wt %, less than 8 wt%, less than 5 wt %, less than 2 wt %, or less than 1 wt % filler, basedon the entire weight of the crosslinkable polymeric composition. Invarious embodiments, the crosslinkable polymeric composition can be freeor substantially free of filler. As used herein with respect to fillercontent, the term “substantially free” denotes a concentration of lessthan 10 parts per million by weight, based on the entire weight of thecrosslinkable polymeric composition.

The crosslinkable polymeric composition may also contain other additivesincluding, but not limited to, antioxidants, crosslinking agents (e.g.,cure boosters or coagents), other polymers beyond those noted above,tree-retardants (e.g., polyethylene glycol, polar polyolefin copolymers,etc.), scorch-retardants, processing aids, fillers, coupling agents,ultraviolet absorbers or stabilizers, antistatic agents, nucleatingagents, slip agents, plasticizers, lubricants, viscosity control agents,tackifiers, anti-blocking agents, surfactants, extender oils, acidscavengers, flame retardants, and metal deactivators. Examples of knowncrosslinking coagents are triallyl isocyanurate, ethoxylated bisphenol Adimethacrylate, α-methyl styrene dimer (AMSD), and other co-agentsdescribed in U.S. Pat. Nos. 5,346,961 and 4,018,852. Additives, otherthan fillers, are typically used in amounts ranging from 0.01 or less to10 or more wt % based on total composition weight.

As mentioned above, an antioxidant can be employed with thecross-linkable polymeric composition. Exemplary antioxidants includehindered phenols (e.g., tetrakis [methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane); phosphites andphosphonites (e.g., tris (2,4-di-t-butylphenyl) phosphate); thiocompounds (e.g., dilaurylthiodipropionate); various siloxanes; andvarious amines (e.g., polymerized 2,2,4-trimethyl-1,2-dihydroquinoline).Antioxidants can be used in amounts of 0.1 to 5 wt % based on the totalweight of the crosslinkable polymeric composition. In the formation ofwire and cable compositions, discussed below, antioxidants may be addedto the system before processing (i.e., prior to extrusion andcrosslinking) of the finished article.

The components of the composition can be blended in any manner and usingany equipment. Typically, the polymers are melt blended with one anotherin conventional mixing equipment, e.g., a BRABENDER™ batch mixer orextruder, to form a relatively homogeneous blend comprising continuous,co-continuous and/or discontinuous phases. The mixing or blending may bedone at, below or above the upper melting temperature (point) of thepolymers. The peroxide and other additives can be added in any manner,including soaking and mixing. In one embodiment, the peroxide and otheradditives are blended with one another and then added to one or more ofthe polymers or polymer blend. In one embodiment the peroxide and otheradditives are added individually. In one embodiment one or more of thecomponents are mixed with one or more of the polymers beforemelt-blending with one another. In one embodiment one or more of theperoxide and other additives are added as a masterbatch either to theblended polymers or to one or more of the polymers prior to meltblending. Typically, the peroxide is the last component to be added toone or more of the polymers or polymer blend although here too, it canbe first soaked or mixed with one or more of the polymers prior to themelt blending of the polymers. In an embodiment, all the ingredients(including peroxide) are melt-blended in one step. In anotherembodiment, all the ingredients (including peroxide) are melt-blended inone step as part of the cable extrusion process, without a need to firstprepare a compound prior to use during cable extrusion.

For example, compounding can be performed by either (1) compounding allcomponents into the ethylene-based interpolymer, or (2) compounding allthe components except for the organic peroxide and other liquidadditives, which may be soaked into the ethylene-based interpolymercomposition after all others have been incorporated. Compounding can beperformed at a temperature of greater than the melting temperature ofthe ethylene-based interpolymer up to a temperature above which theethylene-based interpolymer begins to degrade. In various embodiments,compounding can be performed at a temperature ranging from 100 to 200°C., or from 110 to 150° C. In various embodiments, soaking the organicperoxide and/or other liquid additives into the ethylene-basedinterpolymer or ethylene-based interpolymer composition can be performedat a temperature ranging from 30 to 100° C., from 50 to 90° C., or from60 to 80° C.

The resulting crosslinkable polymeric composition can have a zero shearviscosity at 135° C. of at least 10,000 Pa·s, at least 20,000 Pa·s, orat least 30,000 Pa·s. Additionally, the crosslinkable polymericcomposition can have a zero shear viscosity at 135° C. of up to 400,000Pa·s. Zero shear viscosity is determined according to the proceduredescribed in the Test Methods section, below.

The crosslinkable polymeric composition can have an extensionalviscosity of greater than 200,000 Poise, greater than 225,000 Poise, orgreater than 250,000 Poise when measured at 135° C., 1 s⁻¹, and a Henckystrain of 1. The crosslinkable polymeric composition can have anextensional viscosity up to 10,000,000 Poise at any Hencky strain.Extensional viscosity is determined according to the procedure describedin the Test Methods section, below.

The crosslinkable polymeric composition can have a time for a 1 lb-in.increase in torque (“ts1”) at 140° C. of at least 10 minutes, at least15 minutes, or at least 20 minutes. Additionally, the crosslinkablepolymeric composition can have a ts1 of up to 300 minutes. Determinationof ts1 is done according to the procedure described in the Test Methodssection, below.

Crosslinked Polymeric Composition

The above-described crosslinkable polymeric composition can be cured orallowed to cure in order to form a crosslinked polymeric composition.When a peroxide is employed, such curing can be performed by subjectingthe crosslinkable polymeric composition to elevated temperatures in aheated cure zone, which can be maintained at a temperature in the rangeof 175 to 260° C. The heated cure zone can be heated by pressurizedsteam or inductively heated by pressurized nitrogen gas. Thereafter, thecrosslinked polymeric composition can be cooled (e.g., to ambienttemperature).

Following crosslinking, the crosslinked polymeric composition canundergo degassing to remove at least a portion of the volatiledecomposition byproducts. Degassing can be performed at a degassingtemperature, a degassing pressure, and for a degassing time period toproduce a degassed polymeric composition. In various embodiments, thedegassing temperature can range from 50 to 150° C., or from 60 to 80° C.In an embodiment, the degassing temperature is 65 to 75° C. Degassingcan be conducted under standard atmosphere pressure (i.e., 101,325 Pa).

The extent of crosslinking in the crosslinked polymeric composition canbe determined via analysis on a moving die rheometer (“MDR”) at 182° C.according to ASTM D5289-12. Upon analysis, an increase in torque, asindicated by the difference between the maximum elastic torque (“MH”)and the minimum elastic torque (“ML”) (“MH-ML”), indicates greaterdegree of crosslinking. In various embodiments, the resultingcrosslinked polymeric composition can have an MH-ML of at least 0.2lb-in., at least 0.6 lb-in., at least 1.0 lb-in., at least 1.4 lb-in.,at least 1.8 lb-in., at least 2.0 lb-in, at least 2.5 lb-in., at least3.0 lb-in., or at least 4.0 lb-in. Additionally, the crosslinkedpolymeric composition can have an MH-ML up to 30 lb-in.

In various embodiments, the crosslinked polymeric composition can have aShore D hardness of 40 or less, 35 or less, or 30 or less. Additionally,the crosslinked polymeric composition can have a Shore D hardness of atleast 10. In one or more embodiments, the crosslinked polymericcomposition can have a Shore A hardness of 90 or less, 85 or less, or 80or less. Additionally, the crosslinked polymeric composition can have aShore A hardness of at least 60.

In one or more embodiments, the crosslinkable polymeric composition canhave a gel content of at least 30 wt %, at least 40 wt %, or at least 50wt %. Additionally, the crosslinkable polymeric composition can have agel content up to 99 wt %.

In various embodiments, the crosslinked polymeric composition can have ahot creep of any value, even if not measurable due to insufficientcrosslinking for hot creep to be measurable. In other embodiments, thecrosslinked polymeric composition can have a hot creep value of 200% orless, 150% or less, 75% or less, 50% or less, or 40% or less.

In one or more embodiments, the crosslinked polymeric composition canhave a dissipation factor of less than 8%, less than 4%, less than 1%,or less than 0.7% when measured at 60 Hz, 2 kV, and 130° C.

Coated Conductor

A cable comprising a conductor and an insulation layer can be preparedemploying the above-described crosslinkable polymeric composition. Theabove-described crosslinkable polymeric composition may be used to makeone or more layers of the coated conductor (including insulation,semiconductive shield, and jacket). “Cable” and “power cable” mean atleast one wire or optical fiber within a sheath, e.g., an insulationcovering or a protective outer jacket. Typically, a cable is two or morewires or optical fibers bound together, typically in a common insulationcovering and/or protective jacket. The individual wires or fibers insidethe sheath may be bare, covered or insulated. Combination cables maycontain both electrical wires and optical fibers. Typical cable designsare illustrated in U.S. Pat. Nos. 5,246,783, 6,496,629 and 6,714,707.“Conductor” denotes one or more wire(s) or fiber(s) for conducting heat,light, and/or electricity. The conductor may be a single-wire/fiber or amulti-wire/fiber and may be in strand form or in tubular form.Non-limiting examples of suitable conductors include metals such assilver, gold, copper, carbon, and aluminum. The conductor may also beoptical fiber made from either glass or plastic.

Such a cable can be prepared with various types of extruders (e.g.,single or twin screw types) by extruding the crosslinkable polymericcomposition onto the conductor, either directly or onto an intercedinglayer. A description of a conventional extruder can be found in U.S.Pat. No. 4,857,600. An example of co-extrusion and an extruder thereforecan be found in U.S. Pat. No. 5,575,965.

Following extrusion, the extruded cable can pass into a heated cure zonedownstream of the extrusion die to aid in crosslinking the crosslinkablepolymeric composition and thereby produce a crosslinked polymericcomposition. The heated cure zone can be maintained at a temperature inthe range of 175 to 260° C. In an embodiment, the heated cure zone is acontinuous vulcanization (“CV”) tube. In various embodiments, thecrosslinked polymeric composition can then be cooled and degassed, asdiscussed above.

Alternating current cables prepared according to the present disclosurecan be low voltage, medium voltage, high voltage, or extra-high voltagecables. Further, direct current cables prepared according to the presentdisclosure include high or extra-high voltage cables.

Test Methods

Density

Density is determined according to ASTM D792, Method B in isopropanol.Specimens are measured in an isopropanol bath at 23° C. for 8 minutes toachieve thermal equilibrium prior to measurement.

Melt Index

Melt index, or I₂, is measured in accordance with ASTM D1238, condition190° C./2.16 kg, and is reported in grams eluted per 10 minutes.

Molecular Weight Distribution

A high-temperature gel permeation chromatography (“GPC”) system isemployed, equipped with Robotic Assistant Deliver (“RAD”) system forsample preparation and sample injection. The concentration detector isan Infra-red detector (IR4) from Polymer Char Inc. (Valencia, Spain).Data collection is performed using Polymer Char DM 100 Data acquisitionbox. The carrier solvent is 1,2,4-trichlorobenzene (“TCB”). The systemis equipped with an on-line solvent degas device from Agilent. Thecolumn compartment is operated at 150° C. The columns are four Mixed ALS 30-cm, 20-micron columns. The solvent is nitrogen-purged TCBcontaining approximately 200 ppm 2,6-di-t-butyl-4-methylphenol (“BHT”).The flow rate is 1.0 mL/min, and the injection volume is 200 μl. A 2mg/mL sample concentration is prepared by dissolving the sample innitrogen-purged and preheated TCB (containing 200 ppm BHT) for 2.5 hoursat 160° C. with gentle agitation.

The GPC column set is calibrated by running twenty narrow molecularweight distribution polystyrene (“PS”) standards. The molecular weight(“MW”) of the standards ranges from 580 to 8,400,000 g/mol, and thestandards are contained in six “cocktail” mixtures. Each standardmixture has at least a decade of separation between individual molecularweights. The equivalent polypropylene (“PP”) molecular weights of eachPS standard are calculated by using the following equation, withreported Mark-Houwink coefficients for polypropylene (Th. G. Scholte, N.L. J. Meijerink, H. M. Schoffeleers, and A. M. G. Brands, J. Appl.Polym. Sci., 29, 3763-3782 (1984)) and polystyrene (E. P. Otocka, R. J.Roe, N. Y. Hellman, P. M. Muglia, Macromolecules, 4, 507 (1971)):

$\begin{matrix}{{M_{PP} = \left( \frac{K_{PS}M_{p\; s}^{a_{p\; s} + 1}}{K_{PP}} \right)^{\frac{1}{a_{pp} + 1}}},} & (1)\end{matrix}$where M_(pp) is PP equivalent MW, M_(PS) is PS equivalent MW, log K anda values of Mark-Houwink coefficients for PP and PS are listed below.

Polymer A log K Polypropylene 0.725 −3.721 Polystyrene 0.702 −3.900

A logarithmic molecular weight calibration is generated using a fourthorder polynomial fit as a function of elution volume. Number average andweight average molecular weights are calculated according to thefollowing equations:

$\begin{matrix}{{{Mn} = \frac{\sum\limits^{i}{Wf}_{i}}{\sum\limits^{i}\left( \frac{{Wf}_{i}}{M_{i}} \right)}},} & (2) \\{{{Mw} = \frac{\sum\limits^{i}\left( {{Wf}_{i}*M_{i}} \right)}{\sum\limits^{i}{Wf}_{i}}},} & (3)\end{matrix}$where Wf_(i) and M_(i) are the weight fraction and molecular weight ofelution component i, respectively.Extrusion Evaluation

Extrusion evaluation of the polymers (including ethylene-basedinterpolymers alone or HP LDPE alone) is conducted on a 2.5-inch 24:1L/D extruder using a Maddock screw and 20/40/60/20 mesh screens (at settemperatures of 115.6° C. across all five zones, head and the die). Thescrew speeds range from 25 rpm to 100 rpm. Melt discharge temperature ismeasured by immersing the probe of a hand-held thermocouple (pyrometer)in the molten polymer as it exits the die. This parameter is a measureof the extent of shear-heating prevalent.

Shear Viscosity

To determine the melt-flow properties of polymers and the blends ofethylene-based interpolymers with HP LDPE, dynamic oscillatory shearmeasurements are conducted over a range of 0.1 rad s⁻¹ to 100 rad s⁻¹ ata temperature of 135° C. or 190° C. and 10% strain with stainless steelparallel plates of 25-mm diameter on the strain-controlled rheometerARES/ARES-G2 by TA Instruments. V0.1 and V100 are the viscosities at 0.1and 100 rad s⁻¹, respectively, with V0.1/V100 being a measure of shearthinning characteristics.

To determine the melt-flow properties of the full crosslinkablepolymeric compositions (including peroxide-containing compositions),dynamic oscillatory shear measurements are conducted over a range of 0.1rad s⁻¹ to 100 rad s⁻¹ using a TA Instruments Advanced RheometricExpansion System at a temperature of 135° C. and 0.25% strain. V0.1 andV100 are the viscosities at 0.1 and 100 rad s⁻¹, respectively, withV0.1/V100 being a measure of shear thinning characteristics.

Extensional Viscosity

To determine the melt-extensional properties of the polymers, the blendsof ethylene-based interpolymers with HP LDPE, and the full crosslinkablepolymeric compositions (including peroxide-containing compositions),extensional viscosity is measured using an ARES FCU Rheometer withExtensional Viscosity Fixture Geometry and TA Orchestrator software. Thetest is conducted at a rate of 1/sec at 135° C. to simulate extrusionconditions. The maximum (“peak”) value of viscosity attained isreported, as well as the viscosity at Hencky Strain of 1 and the maximumHencky strain.

Zero Shear Viscosity

Zero shear viscosity is measured from creep recovery (SR-200, 25.0 Pa/3minutes creep/15 minutes recovery/135° C.) on polymers, blends ofethylene-based interpolymers with HP LDPE, or full crosslinkablepolymeric compositions (including peroxide-containing compositions).

Moving Die Rheometer

Moving Die Rheometer (“MDR”) analyses are performed on the compoundsusing Alpha Technologies Rheometer MDR model 2000 unit. Testing is basedon ASTM procedure D5289. The MDR analyses are performed using 6 grams ofmaterial. Samples are tested at 182° C. or at 140° C. at 0.5 degrees arcoscillation for both temperature conditions. Samples are tested onmaterial directly from the Brabender mixing bowl. Resistance topremature crosslinking at extrusion conditions (“scorch”) is assessed byts1 (time for 1 lb-in increase in torque) at 140° C. Ultimate degree ofcrosslinking is reflected by MH (maximum elastic torque)−ML (minimumelastic torque) at 182° C.

Gel Content

Gel content (insoluble fraction) is determined by extracting withdecahydronaphthalene (decalin) according to ASTM D2765. The test isconducted on specimens resulting from MDR experiments at 182° C. A WILEYmill is used (20-mesh screen) to prepare powdered samples, at least onegram of material for each sample. Fabrication of the sample pouches iscrafted carefully to avoid leaks of the powdered samples from the pouch.In any technique used, losses of powder to leaks around the folds orthrough staple holes are to be avoided. The width of the finished pouchis no more than three quarters of an inch, and the length is no morethan two inches. 120 mesh screens are used for pouches. The sample pouchis weighed on an analytical balance. 0.3 grams (+/−0.02 g) of powderedsamples is placed into the pouch. Since it is necessary to pack thesample into the pouch, care is given not to force open the folds in thepouch. The pouches are sealed and samples are then weighed. Samples arethen placed into one liter of boiling decahydronaphthalene (decalin),with 10 grams of 2,2′-methylene-bis (4-methyl-6-tertiary butyl phenol)for 6 hours using flasks in a heated mantle. After the (decalin) hasboiled for six hours, the voltage regulator is turned off leaving thecooling water running until (decalin) has cooled below its flash point(this typically takes at least a half hour). When the (decalin) hascooled, the cooling water is turned off and the pouches removed from theflasks. The pouches are allowed to cool under a hood, to remove as muchsolvent as possible. Then the pouches are placed in a vacuum oven set at150° C. for four hours, maintaining a vacuum of 25 inches of mercury.The pouches are then taken out of the oven and allowed to cool to roomtemperature. Weights are recorded on an analytical balance. Thecalculation for gel extraction is shown below where W1=weight of emptypouch, W2=weight of sample and pouch, W3=weight of sample, pouch andstaple, and W4=weight after extraction.% extracted=((W3−W4)/(W2−W1))×100Gel Content=100−% extractedHot Creep

Hot creep is determined according to ICEA-T-28-562:2003. Hot creeptesting is conducted on 50-mil (1.3-mm) thick samples in an oven with aglass door at 200° C. with 0.2 MPa stress applied to the bottom of thespecimens. Three test specimens for each sample are cut using ASTM D412type-D tensile bars. The samples are elongated for 15 minutes where thepercentage increases in length are measured and the average values ofthe three specimens are reported.

Dissipation Factor

Dissipation factor (“DF”) testing at 60 Hz and 2 kV applied voltage isconducted on crosslinked 50-mil (1.3-mm) plaques. The plaques aredegassed in a vacuum oven at 60° C. for five days. DF testing is carriedout according to ASTM D150 at 60 Hz on a GUILDLINE High VoltageCapacitance Bridge unit, Model 9920A, with a TETTEX specimen holder anda TETTEX AG Instruments Temperature Control Unit. Samples are tested at60 Hz and 2 kV applied voltage at temperatures of 25° C., 40° C., 90°C., and 130° C.

AC Breakdown Strength

AC breakdown strength (“ACBD”), also known as AC dielectric strength, istested with nominal 35-mil (0.9-mm) thick crosslinked plaques on aBRINKMAN AC Dielectric Strength Tester using EXXON Univolt N61transformer oil. Aged samples are aged in a glass U-tube filled with0.01 M sodium chloride solution for twenty one days at 6 kV.

Water Tree Length

Water treeing is initiated in crosslinked plaques in accordance withASTM D6097 and the tree length is measured.

Shore Hardness

Determine Shore A and Shore D hardness at 23° C. according to ASTM D2240on specimens of 250-mil (6.4-mm) thickness and 51-mm diameter, andrecord the average of five measurements.

Flexural Modulus, 2% Secant

Flexural modulus (2% secant), in psi, is measured in accordance withASTM D790. The plaques used for flexural modulus testing are prepared bycompression molding. The composition is pressed under light pressure(6,000 psi for 15 minutes), at 130° C., in a Carver press. The press isthen opened and closed three times to allow the material to soften andair to escape. The pressure is then increased to 15 tons (30,000 lbs),at which time the press platens are cooled to a temperature less than50° C. at a rate of 15° C./minute. Five test bars, each 5 in.×0.5in.×0.125 in., are die cut from the compression molded plaques (10 in.×7in.×0.120 in.). The test involves flexing the bar to failure with aloading nose moving at 0.05 inches/minute, as the bar sits on two radiithat are two inches apart, in accordance with ASTM D790. The datareported herein represents the average flexural modulus of the 5specimens.

Melt Strength

Melt strength of polymers is measured by Rheotens at 190° C. Meltstrength, as used herein, is a maximum tensile force measured on amolten filament of a polymer melt extruded from a capillary rheometerdie at a constant shear rate of 33 reciprocal seconds (sec⁻¹) while thefilament is being stretched by a pair of nip rollers that areaccelerating the filament at a rate of 0.24 centimeters per second persecond (cm/sec²) from an initial speed of 1 cm/sec. The molten filamentis preferably generated by heating 10 grams (g) of a polymer that ispacked into a barrel of an Instron capillary rheometer, equilibratingthe polymer at 135° C. for five minutes and then extruding the polymerat a piston speed of 2.54 cm/minute (cm/min) through a capillary diewith a diameter of 0.21 cm and a length of 4.19 cm. The tensile force ispreferably measured with a Goettfert Rheotens located so that the niprollers are 10 cm directly below a point at which the filament exits thecapillary die.

Materials

The following materials are employed in the Examples, below.

POE-1 is an ethylene/1-octene polyolefin elastomer having a melt index(I₂) of 2.7 g/10 min., and a density of 0.880 g/cm³, which is preparedby The Dow Chemical Company, Midland, Mich., USA. POE-1 is preparedaccording to the following procedure under the conditions provided inTable A, below. A continuous solution polymerization is carried out in acomputer-controlled, continuous stirred tank reactor (“CSTR”). The5-liter reactor is hydraulically full and set to operate at steady stateconditions. Purified Isopar®E, ethylene, 1-octene, and hydrogen aresupplied to the reactor through mass-flow controllers using variablespeed diaphragm pumps that control the flow rates and reactor pressure.The desired temperature is maintained and monitored using an internalthermocouple. At the discharge of the pump, a side stream is taken toprovide flush flows for the catalyst, cocatalyst, and injection linesand the reactor agitator. A slight excess of cocatalyst is used. Theseflows are measured by Micro-Motion mass flow meters and controlled bycontrol valves or by the manual adjustment of needle valves. Theremaining solvent is combined with 1-octene, ethylene, and hydrogen andfed to the reactor. A mass flow controller is used to deliver hydrogento the reactor as needed. The temperature of the solvent/monomersolution is controlled by use of a heat exchanger before entering thereactor. The catalyst is fed to the reactor separately from thecocatalyst. The component solutions are metered using pumps and massflow meters and are combined with the catalyst flush solvent andintroduced into the bottom of the reactor. The reactor is runliquid-full at 410 psig (2.82 MPa) with vigorous stirring. Product isremoved through exit lines at the top of the reactor. Polymerization isstopped by the addition of a small amount of water into the exit linealong with any stabilizers or other additives. Solvent is then removedand the product is recovered using a devolatilizing extruder andwater-cooled pelletizer.

TABLE A Reactor Process Conditions for Preparing POE-1 Parameter UnitPOE-1 Solvent lb/hr 687 Ethylene lb/hr 138 Hydrogen g/hr 5.2 1-Octenelb/hr 70 Feed Temperature ° C. 23.9 Reactor Temperature ° C. 149Catalyst Type Catalyst Catalyst Concentration Wt % 3 Catalyst Flow g/hr6.5 Catalyst Efficiency kg/mg 3.34 Cocatalyst Concentration Wt % 15Cocatalyst Flow g/hr 5.0 Ethylene Conversion % 86.3 Ethylene g/l 16.1Log Viscosity cP 2.74

POE-2 is an ethylene/1-octene polyolefin elastomer having a melt index(I₂) of 4.2 g/10 min., and a density of 0.874 g/cm³, which is preparedby The Dow Chemical Company, Midland, Mich., USA. POE-2 is preparedaccording to the preparation method described above for POE-1 using theconditions provided in Table B, below.

TABLE B Reactor Process Conditions for Preparing POE-2 Parameter UnitPOE-2 Solvent lb/hr 818 Ethylene lb/hr 146 Hydrogen Std cc/min 26551-Octene lb/hr 79.5 Feed Temperature ° C. 30 Reactor Temperature ° C.155 Catalyst Type Catalyst Catalyst Concentration ppm 100 Catalyst Flowlb/hr 1.03 Catalyst Efficiency kg/mg 2.0 Cocatalyst Concentration ppm1177 Cocatalyst Flow lb/hr 0.52 Ethylene Conversion % 82.7 Ethylene g/l16.7 Log Viscosity cPa 2.14

NORDEL™ IP 3722 EL is a hydrocarbon rubber (EPDM) having a density of0.87 g/cm³, a Mooney viscosity at 125° C. of 18 MU, an ethylene contentof 70.5 wt %, and an ethylidene norbornene content of 0.5 wt %, which iscommercially available from The Dow Chemical Company, Midland, Mich.,USA.

LDPE-1 is a high-pressure low-density polyethylene (HP LDPE) having anominal density of 0.919 g/cm³ and a nominal melt index (I₂) of 0.5 g/10min., which is available from The Dow Chemical Company, Midland, Mich.,USA.

LDPE-2 is a high-pressure low-density polyethylene (HP LDPE) having anominal density of 0.922 g/cm³ and a nominal melt index (I₂) of 1.8 g/10min., which is available from The Dow Chemical Company, Midland, Mich.,USA.

ENGAGE™ 7270 is an ethylene/1-butene polyolefin elastomer having adensity of 0.881 g/cm³, a melt index (I₂) of 0.72 g/10 min., and aMooney viscosity (ML 1+4 @ 121° C.) of 24 MU, which is commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

Dicumyl peroxide is commercially available under the trade namePERKADOX™ BC-FF from AkzoNobel Polymer Chemicals LLC, Chicago Ill., USA.

The polyethylene glycol is PEG 20000 (Clariant Polyglykol 20000 SRU),which is a polyethylene glycol having a mean molecular weight of 20000and is commercially available from Clariant Corporation, Charlotte,N.C., USA.

Nofmer MSD, also known as 2,4-diphenyl-4-methyl-1-pentene or α-methylstyrene dimer (“AMSD”), is commercially available from NOF Corporation,Tokyo, Japan.

LOWINOX™ TBM-6 is an antioxidant having the chemical name4,4′-thiobis(2-t-butyl-5-methylphenol), and is commercially availablefrom Addivant Corporation, Danbury, Conn., USA.

SABO™ STAB UV 119 is a high-molecular-weight hindered-amine lightstabilizer having as its main component 1,3,5-triazine-2,4,6-triamine,N2,N2″-1,2-ethanediylbis[N2-[3-[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazin-2-yl]amino]propyl]-N′,N″-dibutyl-N′,N″-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-,which is commercially available from Sabo S.p.A., Bergamo, Italy.

The catalyst used in preparing POE-1 and POE-2 isbis(2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-(4-(2-methyl)propane-2-yl)-2-phenoxy)-1,3-propanediylzirconium (IV), which is prepared according to the synthetic proceduresof U.S. Published Patent Application No. 2004/0010103 A1.

The cocatalyst used in preparing POE-1 and PEO-2 is modifiedmethylaluminoxane, MMAO-3A solution in heptane, which is commerciallyavailable from Akzo Nobel N.V., Amsterdam, Netherlands.

EXAMPLES Example 1

Prepare five Samples (S1-S5) and four Comparative Samples (CS1-CS4)according to the formulations provided in Table 1, below, and thefollowing process. The lab-scale (“lab”) blends are prepared at 170° C.using a Haake Rheomix 3000E mixer with roller style mixing blades atnominal mixing speed of 60 rpm for a period of 5 minutes after all ofthe formulation components are added to the mixing bowl. Largerquantities of select blends are prepared on a 40-mm 44:1 L/Dco-rotating, intermeshing, twin screw extruder (ZSK-40) equipped with anunderwater pelletizing system. A screw speed of 240 rpm and barreltemperature of 190° C. are utilized, and the die is at 220° C.

TABLE 1 Polymer Blend Compositions of S1-S5 and CS1-CS4 POE-1 POE-2ENGAGE ™ 7270 LDPE-1 (wt %) (wt %) (wt %) (wt %) S1 (ZSK-40) 80 — — 20S2 (lab) 80 — — 20 S3 (lab) 70 — — 30 S4 (lab) — 70 — 30 S5 (ZSK-40) —65 — 35 CS1 (lab) 90 — — 10 CS2 (lab) — 90 — 10 CS3 (lab) — 80 — 20CS4(lab) — — 92 8

Analyze S1-S5 and CS1-CS4 along with five additional Comparative Samples(CS5-CS9) according to the procedures provided in the Test Methodssection, above. CS5 is neat LDPE-2, CS6 is neat POE-1, CS7 is neatPOE-2, CS8 is neat NORDEL™ 3722 EL, and CS9 is neat ENGAGE™ 7270.Results are provided in Table 2, below.

TABLE 2 Properties of S1-S6 and CS1-CS7 Max. extens. Flexural viscosityZero Shear Modulus, I₂ Melt Strength V100 V100 at 135° C., ViscosityDensity 2% Secant (g/10 (cN) V0.1/V100 (Pa · s) V0.1/V100 (Pa · s) 1 s⁻¹at 135° C. (g/cm³) (psi) min) @ 190° C. @ 190° C. @ 190° C. @ 135° C. @135° C. (Pa · s) (Pa s) S1 0.884 4,400 1.9 10.0 6.7 858.2 11.8  1719.1347,000 20,020 S2 0.888 4,700 1.9 8.6 5.6 916.5 N/A N/A N/A N/A S3 0.8915,900 1.6 15.1 7.4 885.5 N/A N/A N/A N/A S4 0.887 4,900 2.4 5.4 5.9683.8 N/A N/A N/A N/A S5 0.887 5,200 2.2 11.8 8.1 659.0 13.6  1361.6453,000 16,270 CS1 0.883 3,600 2.2 4.0 4.4 932.4 N/A N/A N/A N/A CS20.883 2,400 3.3 2.0 3.5 719.3 N/A N/A N/A N/A CS3 0.883 3,200 3.1 2.44.5 691.2 N/A N/A N/A N/A CS4 0.884 N/A 0.65 5.6 9.5 1,729 N/A N/A N/AN/A CS5 0.921 26,100  1.9 8.4 16.9 579 38   985  392,000 31,750 CS60.880 2,600 2.7 1.5 3.5 963.3 7.3 2067.5  65,000 N/A CS7 0.874 1,600 4.20.7 2.9 724.3 5.2 1530.3  34,000 N/A CS8 0.872 N/A 0.70 7.0 33 1,514 N/AN/A N/A N/A CS9 0.881 N/A 0.72 4.9 7.4 1,845 N/A N/A N/A N/A

The results provided in Table 2 show a significant increase in meltstrength and shear thinning ratio (V0.1/V100) when adding ahigh-pressure LDPE to an ethylene-based interpolymer. However, of thepolymer blend compositions and neat polymers, only S1 to S5 exhibit thefollowing desirable combination of properties: V100 of less than 1,300Pa·s (at 190° C.), V0.1/V100 of at least 5 (at 190° C.), melt strengthgreater than 4 cN (at 190° C.), and flexural modulus less than 25,000psi.

Example 2

Evaluate the extrusion characteristics of S1, S5, CS6, and CS8 accordingto the procedures provided in the Test Methods section, above. Theresults are provided in Table 3, below.

TABLE 3 Extrusion Characteristics of S1, S5, CS6, and CS8 S1 S5 CS6 CS8Melt Discharge Temperature During Extrusion (° C.) @ 25 rpm 127.8 125.6132.2 129.4 @ 50 rpm 152.2 145.6 153.3 157.8 @ 75 rpm 171.7 161.1 173.9184.4 @ 100 rpm 188.9 173.9 192.2 207.8 Extrusion rate (lb/hr) @ 25 rpm48.8 46.8 50.5 49.0 @ 50 rpm 100.8 102.0 101.4 99.4 @ 75 rpm 150.6 156.6153.6 150.0 @ 100 rpm 204.6 204.0 207.6 201.0 Extrusion Rate at MeltDischarge 86 101 81 77 Temp. of 145° C. (lb/hr)

The results in Table 3 show that the HP LDPE blends with ethylene-basedinterpolymers (S1 and S5) exhibit desirably lower melt temperaturesduring extrusion at screw speeds up to 100 rpm and relatively greaterextrusion rates at a melt discharge temperature of 145° C. Lower melttemperatures are considered in using such polymer compositions tomanufacture electrical insulation compounds containing peroxides, so asto avoid premature crosslinking during extrusion of said insulationcompounds. Note that a melt discharge temperature of 145° C. is close tothe maximum practiced industrially with compositions containing dicumylperoxide, in the manufacture of power cables.

It is noteworthy that the measured extrusion rate in lb/hr at meltdischarge temperature of 145° C. given in Table 3 (“X”) tends tocorrelate with the measured V100 in Pa·s @ 190° C. given in Table 2(“Y”), and is described by the following equation, for the assessedcompositions:Y=12124e ^(−0.029X)(R ²=0.8); over a “Y” range of 659 to 1541 Pa sY=4327.3e ^(−0.019X)(R ²=1.0); over a “Y” range of 659 to 963 Pa s

Example 3

Prepare two additional Samples (S6 and S7) and three additionalComparative Samples (CS10, CS11, and CS12) according to the formulationsprovided in Table 4, below, and the following procedure. Melt thedicumyl peroxide by heating to 60° C. then mix with the Nofmer MSD at a5:1 ratio (of peroxide to Nofmer MSD). Prepare a “solids” mixture bymixing everything (except peroxide and Nofmer MSD) in a container byhand. Next, compound the solids mixture in a 250-cm³ Brabender batchmixer with cam rotors at 190° C. and 40 rpm for 5 minutes. The resultingblend is removed from the mixer, cold pressed into a thin sheet, cutinto strips, and fed through a pelletizer to make pellets. The polymerpellets are heated in a glass jar at 60° C. for 2 hours and subsequentlysprayed with the stipulated amount of peroxide/Nofmer MSD mixture usinga syringe. The jar is tumble-blended for 10 minutes at room temperatureand heated at 50° C. for 16 hours. Next, the contents of the jar aremixed in a 250-cm³ Brabender mixing bowl with cam rotors at 120° C. and30 rpm for 10 minutes (after loading).

TABLE 4 Compositions of S6, S7, CS10, CS11, and CS12 S6 S7 CS10 CS11CS12 Polymer Blend of S1 96.48 — — — — (wt %) Polymer Blend of S5 —96.48 — — — (wt %) POE-2 (wt %) — — 97.01 — — NORDEL ™ 3722 — — — 97.01— (wt %) LDPE-2 96.48 Dicumyl Peroxide (wt %) 2.00 2.00 1.80 1.80 2.00PEG 20000 (wt %) 0.58 0.58 0.29 0.29 0.58 LOWINOX ™ TBM-6 0.34 0.34 0.340.34 0.34 (wt %) SABO ™ STAB UV 119 0.20 0.20 0.20 0.20 0.20 (wt %)Nofmer MSD (wt %) 0.40 0.40 0.36 0.36 0.40 Total: 100.00 100.00 100.00100.00 100.00

Analyze S6, S7, CS10, CS11, and CS12 in a moving die rheometer at 140°C. or 182° C. for evaluation of crosslinking characteristics. For meltrheological measurements, the compositions are compression molded at thefollowing conditions to prevent significant crosslinking: 500 psi (3.5MPa) at 120° C. for 3 minutes, followed by 2500 psi (17 MPa) at thistemperature for 3 minutes, cooling to 30° C. at this pressure, andopening the press to remove the molded plaque. For electrical andmechanical measurements, the compositions are compression molded at thefollowing conditions to make completely crosslinked specimens ofdifferent dimensions: 500 psi (3.5 MPa) at 125° C. for 3 minutes,followed by 2500 psi (17 MPa) at 180° C. for 20 minutes, cooling to 30°C. at this pressure, and opening the press to remove the molded plaque.Analyze each of S6, S7, CS10, CS11, and CS12 according to the proceduresprovided in the Test Methods section, above. Results are provided inTable 5, below.

TABLE 5 Properties of S6, S7, CS10, CS11, and CS12 S6 S7 CS10 CS11 CS12V0.1/V100 (135° C.) 22.6 21.8 N/A N/A 47.7 V100 at 135° C. (Pa · s)1,387 1,058 N/A N/A 717 Extensional Viscosity 580,180 483,380 N/A N/A557,040 at 135° C., 1 s⁻¹ and Hencky Strain of 1 (Poise) Maximumextensional 6,371,300 3,277,800 N/A N/A 4,001,600 viscosity at 135° C.,1 s⁻¹ (Poise) Hencky Strain at 4.1 3.6 N/A N/A 3.7 Maximum ExtensionalViscosity Zero Shear Viscosity 48,150 58,090 N/A N/A 92,300 at 135° C.(Pa · s) ts1at 140° C. (minutes) 31.1 38.8 28.5 31.6 54.7 MH-ML at 182°C. (lb-in.) 5.1 4.1 5.7 5.2 3.1 Gel content (wt %) 89 88 97 87 82 aftercrosslinking Hot creep at 200° C. 32 37 19 23 39 (%) after crosslinkingDissipation factor at 0.15 0.50 0.13 2.67 0.09 2 kV, 130° C., 60 Hz (%)after crosslinking Hardness (Shore D) 30.0 30.3 26.2 24.2 46.1 aftercrosslinking Hardness (Shore A) 85.6 86.6 81.9 80.8 97.2 aftercrosslinking AC Breakdown Strength - 39.4 39.6 33.6 34.3 39.7 unaged(kV/mm) AC Breakdown Strength - 37.1 37.6 31.3 31.2 41.4 aged (kV/mm)Water Tree Length (mm) 0.07 0.05 N/A N/A 0.20

The results provided in Table 5 show insulation compositions in SamplesS6 and S7 that have satisfactory melt rheological properties (at atemperature of 135° C., representative of cable extrusion conditions),crosslinking characteristics, electrical properties, water tree length,and hardness.

Example 4

Prepare one additional Sample (S8) and two additional ComparativeSamples (CS13-CS14) according to the formulations provided in Table 6,below, and the following process. The lab-scale (“lab”) blends areprepared at 170° C. using a Haake Rheomix 3000E mixer with roller stylemixing blades at nominal mixing speed of 60 rpm for a period of 5minutes after all of the formulation components are added to the mixingbowl.

TABLE 6 Compositions of S8, CS13, and CS14 NORDEL 3722 LDPE-1 (wt %) (wt%) S8 (lab) 70 30 CS13 (lab) 90 10 CS14 (lab) 80 20

Analyze S8, CS13, and CS14 along with two additional Comparative Samples(CS15 and CS16) according to the procedures provided in the Test Methodssection, above. CS15 is neat LDPE-2, and CS16 is neat NORDEL™ 3722 EL.Results are provided in Table 7, below.

TABLE 7 Properties of S8, CS13, CS14, CS15, and CS16 Flexural Modulus,Melt Strength V100 Density 2% Secant I₂ (cN) V0.1/V100 (Pa · s) (g/cm³)(psi) (g/10 min) @ 190° C. @ 190° C. @ 190° C. S8 0.890 4,400 0.17 16.434.9 1,221 CS13 0.881 2,600 0.16 8.6 32.7 1,368 CS14 0.886 3,400 0.1512.0 33.9 1,329 CS15 0.922 28,300 1.7 8.4 21.6 614 CS16 0.877 1,700 1.26.2 31.8 1,474

The results provided in Table 7 demonstrate a significant increase inmelt strength and shear thinning ratio (V0.1/V100) when adding ahigh-pressure LDPE to an ethylene-based interpolymer. However, of thepolymer blend compositions and neat polymers, only S8 exhibits thefollowing desirable combination of properties: V100 of less than 1,300Pa·s (at 190° C.), V0.1/V100 of at least 5 (at 190° C.), melt strengthgreater than 4 cN (at 190° C.) and flexural modulus less than 25,000psi.

The invention claimed is:
 1. A crosslinkable polymeric compositioncomprising: (a) a polymer blend comprising: (1) 10 to 94 weight percent,based on the total weight of said crosslinkable polymeric composition,of an ethylene-based interpolymer having the following properties: (i) adensity of 0.93 g/cm3 or less, (ii) a melt index (I2) at 190° C. ofgreater than 0.2 g/10 minutes, and (iii) a shear thinning ratio(V0.1/V100) at 190° C. and 10% strain of less than 8; and (2) 5 to 90weight percent, based on the total weight of said crosslinkablepolymeric composition, of a high-pressure polyethylene; and (b) 0 toless than 40 weight percent, based on the total weight of saidcrosslinkable polymeric composition, of a filler, wherein saidethylene-based interpolymer of component (a) is not prepared in ahigh-pressure reactor or process, wherein said polymer blend has thefollowing properties: (i) a shear thinning ratio (V0.1/V100) at 190° C.and 10% strain of at least 5, (ii) a high-shear viscosity (V100) at 190°C. and 10% strain of less than 1,300 Pa·s, (iii) a melt strength of atleast 4 centiNewtons at 190° C., and (iv) a flexural modulus, 2% secant,of less than 25,000 psi.
 2. The crosslinkable polymeric composition ofclaim 1, wherein said polymer blend has a shear thinning ratio(V0.1/V100) at 190° C. and 10% strain of at least 10% greater than theshear thinning ratio of said ethylene-based interpolymer.
 3. Thecrosslinkable polymeric composition of either claim 1, wherein saidhigh-pressure polyethylene is present in an amount ranging from 20 to 35weight percent based on the total weight of said polymer blend, whereinsaid polymer blend exhibits a melt strength of at least 5 centiNewtonsat 190° C.
 4. The crosslinkable polymeric composition of claim 1,wherein said crosslinkable polymeric composition is renderedcrosslinkable by further comprising (c) an organic peroxide in an amountof at least 0.5 weight percent based on the total weight of saidcrosslinkable polymeric composition.
 5. The crosslinkable polymericcomposition of claim 1, wherein said ethylene-based interpolymer is anethylene/1-octene copolymer.
 6. The crosslinkable polymeric compositionof claim 1, wherein said filler is present in an amount greater than 0weight percent to less than 40 weight percent, wherein said filler isselected from the group consisting of heat-treated clay, surface-treatedclay, and organoclay.
 7. The crosslinkable polymeric composition ofclaim 1, wherein said crosslinkable polymeric composition has one ormore of the following properties: (i) a zero shear viscosity at 135° C.of at least 10,000 Pas; (ii) an extensional viscosity of greater than200,000 Poise when measured at 135° C., 1 s−1, and a Hencky strain of 1;and (iii) a ts1 at 140° C. of at least 10 minutes.
 8. A crosslinkedpolymeric composition prepared from the crosslinkable polymericcomposition of claim
 1. 9. The crosslinked polymeric composition ofclaim 8, wherein said crosslinked polymeric composition has one or moreof the following properties: (i) an MH-ML at 182° C. of at least 0.2lb-in.; (ii) a shore D hardness of 40 or less; (iii) a shore A hardnessof 90 or less; (iv) a gel content of at least 30%; (v) a hot creep valueof 200% or less; and (vi) a dissipation factor of less than 8% whenmeasured at 60 Hz, 2 kV, and 130° C.
 10. A coated conductor comprising:(a) a conductor; and (b) an insulation layer at least partiallysurrounding said conductor, wherein at least a portion of saidinsulation layer is formed from at least a portion of said crosslinkedpolymeric composition of claim 8.